CYP27A1 and cataract: Other genes whose increased expression or mutations have resulted in clinical signs of retinal damage (CXCR1, CXCR2) or cataracts in humans and animal models (CRYBA2) or have been directly associated with CEA disease in breeds related to Collies (NHEJ1) are located within 1 Mb of the CYP27A1 gene from upstream and downstream (Figure 3).